We seek continued support of the Waisman Center Intellectual and Developmental Disabilities Research Center, a comprehensive interdisciplinary program focused on IDD spanning the biological, biobehavioral, and bio-behavioral sciences. The Waisman IDDRC brings together 46 PIs from 21 academic departments from the UW-Madison's Schools of Medicine and Public Health, Veterinary Medicine, Pharmacy, Agriculture and Life Sciences, Letters and Science, Education, Engineering, and Human Ecology. This application requests support for an Administrative Core (Core A), providing scientific leadership, program and faculty development, facilitation of interdisciplinary collaboration, and biostatistical and bioinformatics expertise; and three innovative scientific core services: Clinical Translational (Core B), providing services, resources, and training in the recruitment of human participants, clinical assessment, behavioral methods development, and cGMP biomanufacturing of therapeutics; Brain Imaging (Core C), providing access to state-of-the-art neuroimaging instrumentation (3T MRI, PET, and microPET scanners for human, non-human primate, and rodent scanning, and an EEG recording system), as well as expertise and tools for image acquisition and analysis; and IDD Models (Core D), providing resources, expertise, and technical services in the generation and characterization of mutant or genetically engineered strains of mice and rats, the generation of induced pluripotent stem cell lines from humans with IDD conditions, and facilities for phenotypic characterization of these models using molecular, cellular and behavioral technologies. In addition, we request support for a Research Project that is focused on the impact of variations in CGG repeat length in the FMR1 gene on health and function at the cellular through organismal level, using both cell culture models and human subjects. We propose to provide core support to 79 research projects headed by 46 PIs addressing three broad themes relevant to IDD: 1) nervous system development and pathogenesis, 2) IDD conditions, and 3) assessment, interventions, and therapeutics. Collectively the core services and the research project of the Waisman Center IDDRC will stimulate new interdisciplinary IDD research and enhance existing IDD investigations sharpening our focus on discovery, prevention, and treatment for IDD conditions, and improvement of the quality of life of individuals with IDD and their families.